The move will also make Amazon a bigger threat to department stores like Macy’s, Nordstrom, and JCPenney, which have been battling years of declining shopper traffic to malls.

Prior to news of its new athleisure brand, Amazon was already expected to surpass Macy’s to become the biggest apparel seller in the US this year, according to a 58-page report published by Cowen & Co. in October.

The company’s clothing and accessory sales are expected to grow nearly 30% next year, to $28 billion, according to the Cowen analysts. Macy’s apparel sales, by comparison, are expected to drop 4%, to $22 billion, in the period.

As Amazon’s sales grow, so will its share of the apparel market in the US.

Amazon currently claims about 6.6% of the market. That share is expected to increase to 8.2% by next year and further expand to 16.2% within five years, according to Cowen analysts.

By 2021, Cowen expects Amazon to generate $62 billion in annual apparel sales. TJ Maxx is expected to be the No. 2 clothing seller, with $26 billion in sales, and Macy’s is expected to claim the No. 3 spot, with $23 billion in sales.

The company has also hired executives from luxury fashion companies, such as Julie Gilhart, the Barneys New York fashion director whom Amazon reportedly hired as a consultant, and Vogue editor Caroline Palmer.

Also in the past few years, Amazon has started to shift its fashion strategy toward offering more high-end designer names such as Zac Posen and Stuart Weitzman.